Vehicles with internal combustion engines may start and stop to conserve fossil fuels. The engine may be stopped by turning off the ignition or shutting down the fuel supply. The engine may be stopped while the vehicle is standing at a stop light. The engine may also be stopped in preparation for a vehicle stop. For example, the engine may be stopped when the vehicle brakes are applied and the vehicle speed is below a particular speed. Engine stops and starts may reduce power available to auxiliary devices during degraded road conditions.